Florida police officials have ruled the fire that destroyed retired tennis ace James Blake's mansion, killing four people, was part of a murder-suicide.

According to Tmz.com, Darrin Campbell, who was renting the home at the time of the blaze, shot his wife, Kimberly, and two children, Colin and Megan, before setting the home on fire on Wednesday (07May14).

A neighbour called police when she saw flames coming from the mansion and when firefighters arrived on the scene, they discovered fireworks, which Campbell purchased days before the tragedy, going off around the house.

An automatic weapon registered to Darrin was also found at the home.

Police are now investigating Darrin's affairs in a bid to establish a motive.